AAA has a gas price estimator that estimates how much your trip will cost in gas based on average regional gas prices, miles per gallon and the make and model of your car.
Sadly, the interface is horribly ugly – even the Web page is built in tables – and the vehicle year doesn’t go any further back than 1998. Also, given the miles per gallon and average gas prices, why do they need the make and model of the car?
Still, another example of what can be done with a question, a computer, and a little programming.